Just installed Pro 1 Performance Exhaust on my 2007 Mercedes SL550. No bumber cutting required! The resonators were removed as well.

Wow, it sounds amazing!

How is the cabin noise after the installation? I use to have my rear mufflers removed and had straight pipes instead on my 2003 SL 500 but the cabin noise was horrible. I had to put them the mufflers back! I can't stand the drone when on cruising speed.

Is there any performance gains besides the noise?

Are you sure it doesn't require any bumper cutting to fit in the quad pipes? Is that the same for 2003 models?

Is this the part you got? http://topspeedauto.com/mercedes-ben...ad-round-tips/

Thanks!

The cabin noise is minimal at cruising speed and under load with the top up. With the top down, it's much more noticeable but not unbearable. I haven't been able to determine if there has been any hp gain. It's hard to differentiate whether the car is faster or it just sounds faster but I'm sure some hp was added. There was no bumper cutting done. The tips fit perfectly in the bumper. Yes, that is the exact exhaust system I purchased. It should fit your 03. I would recommend getting it. Straight pipes are a little too much for my taste but these generate a great sound along with volume. Also, I removed the resonators as well but if you want to tone it down, just leave them on. Either way, you can't beat the price for this sound!

I'm charging up the GoPro so I can get you more video soon.

Beautiful